1. Field of the Invention
The present invention generally relates to a method and apparatus for fabricating devices on a semiconductor substrate. More specifically, the present invention relates to a method and apparatus for removing halogen-containing residue after plasma etching a conducting or semiconducting layer.
2. Description of the Related Art
Ultra-large-scale integrated (ULSI) circuits may include more than one million electronic devices (e.g., transistors) that are formed on a semiconductor substrate, such as a silicon (Si) wafer, and cooperate to perform various functions within the device. Typically, the transistors used in the ULSI circuits are complementary metal-oxide-semiconductor (CMOS) field effect transistors. A CMOS transistor has a gate structure comprising a polysilicon gate electrode and gate dielectric and is disposed between a source region and drain regions that are formed in the wafer.
Fabrication of the electronic devices comprises etch processes in which one or more layers of a film stack (e.g., film stack of the gate structure) are plasma etched and removed, either partially or in total. During plasma etch processes, the layers (e.g., layers of silicon, polysilicon, hafnium dioxide (HfO2), silicon dioxide (SiO2), and the like) are typically exposed to etchants comprising at least one halogen-containing gas, such as hydrogen bromide (HBr), chlorine (Cl2), carbon tetrafluoride (CF4), carbon monoxide (CO), and the like. Such processes cause a halogen-containing residue to build up on the surfaces of the etched features, etch masks, and elsewhere on the wafer.
When exposed to a non-vacuumed environment (e.g., within factory interfaces that interconnect various wafer processing systems) and/or during consecutive processing, the halogen-containing residues release gaseous halogens and halogen-based reactants (e.g., bromine (Br2), chlorine, hydrogen chloride (HCl), and the like). The released halogens and halogen-based reactants cause corrosion and particle contamination of the interior of the processing systems and factory interfaces, as well as corrosion of metallic layers on the substrate. Cleaning of the processing systems and factory interfaces and replacement of the corroded parts is a time consuming and expensive procedure.
Therefore, there is a need in the art for a method of removing a halogen-containing residue from a substrate during fabrication of CMOS transistors and other devices used in the integrated circuits.